Monitoring systems may be used to monitor transportation of goods from one location to another. For example, a monitoring system may be used to track the movement of a truck, car, ship, or other transportation vehicle as the vehicle travels to a destination to deliver goods. A portable monitoring device may be attached to the vehicle or goods in the vehicle and used to track the location of the vehicle as well as monitor various conditions in the vehicle. The portable monitoring device may be used to support various monitoring activities at the vehicle or remotely from the vehicle, including monitoring vehicle conditions (e.g., temperature inside the vehicle), a location of the vehicle relative to its destination or path, a current vehicle status (e.g., if the vehicle is stopped or moving slowly). The monitoring activities may further include monitoring the battery or power supply of the portable monitoring device itself.